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cell membrane
biol 1210
| Term | Definition |
|---|---|
| basic structure of cell membrane | bilayer of phospholipids. The hydrophilic heads interact with water while the hydrophobic tails interact with one another |
| lipids do no form polymers, unlike the other biological macromolecules. T/F | T |
| what are lipids made of? how does this impact polarity? | consist mostly of nonpolar carbon-hydrogen bonds and a little bit of O, are thus hydrophobic |
| 3 groups of lipids & which have fatty acids | triglycerides, steroids, phospholipids. All have fatty acids |
| fatty acids | long chains of carbons attached to a carboxyl group at one end |
| saturated v. unsaturated fatty acid | saturated: single-bonded C chain with H bonded to all other sites; unsaturated: C chain with double-bonded C atoms in centre -> less H (double bond takes up H bonding sites) & a "kink" in the chain |
| triglycerides | aka fats, 3 fatty acids linked to 1 glycerol molecule. Each fatty acid is linked to glycerol via dehydration reaction. Mainly function as energy storage |
| phospholipids | 2 fatty acids & a phosphate group attached to glycerol. Most have 1 saturated fatty acid tail and 1 unsaturated tail. Phosphate group forms a negatively charged, polar 'head' and fatty acid chains form hydrophobic 'tail' |
| what happens when phospholipids are added to water? | they self-assemble into a phospholipid bilayer with hydrophobic tails pointing towards the interior and each other, polar heads facing outwards. |
| amphipathic | "dual property" - refers to molecules that have both hydrophilic and hydrophobic components |
| steroids | lipids characterized by a C chain consisting of 4 fused rings. Important steroid: cholesterol - component in animal cell membranes & precursor for some steroid hormones |
| plasma membrane | boundary that separates the living cell from its surroundings & compartments in cells. Exhibits selective permeability |
| selective permeability | capacity to cross; allowing some substances to cross it more easily than others - hydrophobic outside & interior hydrophobic region |
| mosaic of cell membrane | some proteins & carbs are part of membrane composition, making it a mosaic |
| describe fluidity of the cell membrane | the interactions between phospholipids are weak, they move in the membrane's plane. Thus, membrane is fluid & dynamic mosaic. Lipids rapidly move laterally, rarely flip-flop. Fluid to function, but not TOO fluid. |
| types of membrane proteins | peripheral proteins, integral proteins, transmembrane proteins. Types of proteins in the membrane mosaic determine most of membrane's specific functions, which differ based on cell type |
| peripheral proteins | on the membrane surface, ionic and H-bond interactions with hydrophilic lipid & protein groups, only in the hydrophobic region |
| integral proteins | possess hydrophobic domains which are anchored to hydrophobic lipids, partially in cell membrane |
| transmembrane proteins | span the membrane, hydrophilic & hydrophobic regions. Allow for the passage of hydrophilic things - can be enzymes, receptors, cell recognition, intracellular joining, cytoskeleton attachment to extracellular matric |
| why are flip-flops rare events in the movement of the phospholipids? | the ends are differing hydrophilic/hydrophobic - to flip-flip, the hydrophilic head hast to move into the hydrophobic region |
| describe carbohydrate function in cell membranes | carbs bond covalently in the membrane to proteins (form glycoproteins) or lipids (form glycolipids). On external side of membrane, carbs vary among species, individual and even cell types. Important in cell-cell recognition |
| what may effect membrane fluidity & permeability? | as fluid & dynamic mosaic, fluidity & permeability of membrane may change depending on its composition & the environment |
| cell membrane fluidity | the ability of molecules to move in the membrane/viscosity of the membrane. Affects the diffusion of proteins & other molecules inside cells, thus affecting their function. Fluidity is affected by phospholipid structure, cholesterol composition, & temp |
| cell membrane permeability | the rate of diffusion of molecules across the membrane/how easily molecules pass thru the membrane barrier. Fluidity can affect membrane permeability. Majorly impacted by transport proteins |
| cell membrane fluidity & temperature | as temperatures increase, membrane move from solid (gel) state -> move fluid state = increases permeability. Cold environment usually compresses membranes, makes them less fluid, less permeable & more susceptible to rupture |
| cell membrane & cholesterol | cholesterol regulates temp. as a buffer of fluidity in the cell membrane. Component of animal cell membranes. |
| chemical structure of cholesterol | Amphipathic: hydrophilic hydroxyl group and a hydrophobic region at 4 interconnected carbon rings. |
| cholesterol & cell membrane fluidity at normal (warm) temps | cholesterol decreases membrane fluidity by restraining the movement of phospholipids - prevents them from falling apart |
| cholesterol & cell membrane fluidity at cool temps | cholesterol increases membrane fluidity by preventing phospholipids from packing tightly - prevents membrane from getting dense & breaking |
Created by:
AntBanana
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